The northern clingfish is a fish that sucks like crazy -- literally. Equipped with a large adhesion disc covering around 25 percent of its belly, this evolutionary trait allows the saltwater-dwelling clingfish (Gobiesox maeandricus) to survive by clinging to rocks and hunt in the turbulent currents of the Pacific Coast of North America.

Hoping to learn more about this trait and to apply it to uses in medicine, researchers from the University of Washington wondered how the clingfish could achieve this "death-grip" in its suction cup, and derived a series of experiments to test and compare the fish's suction powers to those of man-made suction cups, on a variety of surfaces.

According to LiveScience, they used dead clingfish in their experiments, to ensure that the results were due to the structure of the suction disc (apparently, dead clingfish retain up to 96 percent of a live clingfish's clinging power). Using harnesses, a machine and a measuring device to pull these discs off different textured surfaces, they found that the clingfish's disc can generate adhesive forces 80 to 230 times their body weight, allowing this tiny fish to hang onto rocks, and to hunt limpets (round molluscs that also cling to rocks).

It's all in the microvilli

Eager to find the secret behind the clingfish's amazing ability, the researchers tested and ruled out fish mucus as a contributing factor, and finally discovered that it had to do with the structure of the disc itself:

The team instead found that the secret to the clingfish's adhesion is the hierarchically structured microvilli (tiny hairs similar to those found on gecko and spider feet) around the edges of the adhesive disc. When you pull on a suction cup, its sides slide inward; however, the fish's microvilli induce high friction to prevent slipping. Additionally, the disc's flexibility and microvilli help seal its edges to rough surfaces, preventing liquids from leaking in and disrupting the adhesion.

It's a fascinating insight into nature's design for this tenacious fish; more over at LiveScience.